Off set crank grinding

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rumblefish360

rumblefish360

I have escaped the EVIL Empire State!
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Hey! I gotta question!

What is the max stroke you can get from a OE Chrysler small block crank?
340 or 360 cranks? I myself have 360's. so that's where my query really is.
Use of the smaller gerneric rods sizes (AKA Chevy rods) help in this area, but to what limit?

Who has done it?
 
Good question... Im tuned in... I hear of chevy guys doing this and running honda rods. I know a guy who is running a small block 400 chevy crank (w lots of machine work) in a mopar X block w 4.1 bore and W5 heads (he works at the machine shop so all work and hrs are only time. He CLAIMS the chevy cranks are lighter, stronger, with many more rods and pistons to choose from. I believe the 400 is a 3.75 stroke. I know his combo works pretty well. He is turning 5.90s in the 1/8th in an all metal Duster. Not so sure, id want to work on it, but what ever works I guess
 
Yes you can do it.

If you took a 2.125 mopar to a 2.000 chevy, you can add 1/2 the difference in diameter to stroke. The 3.58 becomes about a 3.65 stroke. It really doesn't provide a lot.
 
I wonder if this would provide any opportunities for those old racing cranks?

Say for example the 273/318/340 main journal sized - forged 'yellow steel' 3.51" crankshafts?

Do people ever go beyond chevy & use the 4340 honda rods any? Or does that require the use of custom pistons outside of the +4.00" bore range? Perhaps with an early 318 overbored into 4 inches..?
 
greymouser7 said:
I wonder if this would provide any opportunities for those old racing cranks?

Say for example the 273/318/340 main journal sized - forged 'yellow steel' 3.51" crankshafts?

Do people ever go beyond chevy & use the 4340 honda rods any? Or does that require the use of custom pistons outside of the +4.00" bore range? Perhaps with an early 318 overbored into 4 inches..?
Click to expand...

I think the honda rods have a 1.85" journal. Chevy is 2". Not sure at what point is to much and it will just break anyways.
 
I plan on building a slant with an offset grind crank. going from a stock 4.125 to a 4.5 and running 440 7.1 rods with chevy ends, maybe even a chevy 305 piston
 
crackedback said:
Yes you can do it.

If you took a 2.125 mopar to a 2.000 chevy, you can add 1/2 the difference in diameter to stroke. The 3.58 becomes about a 3.65 stroke. It really doesn't provide a lot.
Click to expand...

True, I was doing some calc's. a .060 360 = 370. The addition of the crank throw increase to 3.65 yields 8 cubes to 378.
4.03 = 372
4.07 = 379
4.10 = 385 (340 guys here!)

MoPar used to offer lots-O-stroker cranks and pistons to match. Though I never investigated the cost. I wonder what a set of cast slugs would run. I know the forged would be pricey.
 
805moparkid said:
I plan on building a slant with an offset grind crank. going from a stock 4.125 to a 4.5 and running 440 7.1 rods with chevy ends, maybe even a chevy 305 piston
Click to expand...

What displacement does this put you at?

Maybe you should start with an Aussie 265 Hemi?

If only you could have a cylinder head CNC'd out of aluminum...:happy1:
 
I love running numbers, and this can make for a cool discussion, but i'm afraid in the end, the real numbers are = $$$. :D

If the Powerball comes my way, i'll distribute enough to you guys for our own "engine challenge". How cool would that be???
 
OldmanRick said:
I love running numbers, and this can make for a cool discussion, but i'm afraid in the end, the real numbers are = $$$. :D

If the Powerball comes my way, i'll distribute enough to you guys for our own "engine challenge". How cool would that be???
Click to expand...

And finding pistons with the correct compression height to work with the off set ground cranks...
 
Exactly. It's an expensive proposal no matter which you go. It's best to stick with off the shelf parts. At least best for the budget.
 
greymouser7 said:
What displacement does this put you at?

Maybe you should start with an Aussie 265 Hemi?

If only you could have a cylinder head CNC'd out of aluminum...:happy1:
Click to expand...

the 265 is a completely different motor and wont fit without some work in an american body.

but it is almost 300ci
 
How far do original 360 set in the hole? off set grind to make it a flat top "0" deck piston.

How much is offset grinding over regular grinding?
 
The only problem I see in making use of the OE piston IF it could make the distance close to the deck would be valve contact. The number 1w&c gave works out to be .0625 added to the throw up top. So, if a stock slug is down .080 in the hole.... .0175 is left up top.

OK, the calc numbers are loose. We know this. (Right?!?!)

It maybe possible to use the customized Chevy slugs designed for there 18* head conversion. You know the heads... The ones that they pay dearly for in a copy cat attempt.
Off hand, I do not know of a low compression slug that has valve reliefs that maybe deep enough to use.

Another thing comes to mind. How far can you go with slugs NOT designed for this. As in OE slugs or after market units skirt length? More food for thought my freinds.
 
Cudafever said:
How far do original 360 set in the hole? off set grind to make it a flat top "0" deck piston.

How much is offset grinding over regular grinding?
Click to expand...

Then the valve reliefs you'd need would cut holes in the pistons.
 
If the deck is thick enough for the intended valve lift.

The above sentence is a broad one in that this should be thought about. A known crown thickness should be a available from the after market. But what about the stock slugs? A while back, a member did a 360 crank into a 318. The pistons ran above deck I think. But he cut the slugs crown for valve reliefs IIRC.

Hughes engines offers this tool for rental.
 
Where does the "big end" width of the available rods fit in here? I've put together Mopar and Chevy small blocks before, but i honestly don't remember those measurements. As far as the Honda rod.....you got me???
 
lets have a moment of review...

spent extra money to have crank off set ground...

spend extra money to buy SB chevy rods to fit offset crank...

spend extra money to have oem pistons notched..went they their pin size is .984..and the sb chevy has a .927 pin size....

LOL
 
Rick, the after market has what they call generic rods. They are so made in widths to fit the verity of cranks out there. You can purchase these rods to fit and work in a MoPar engine, big and small block with the crank modified for the smaller big end.

The other rods I have no idea what there talking about or what they could fit. I really don't give a rats *** about a /6 or Aussie HEMI 6. But there engines could have a bennifit or bennifit from the same idea and if possible, there call and what the heck. Have at it and have fun with it.

I myself am just interested about the 360. Though any info on a y engine is good and welcomed. So far, if it'll work on a 360, I missed it. I see the idea of the smaller big end of the other rod mentioned. But know nothing else about it.

Length strength width weight power handling

Tony, your point is well taken to a point. What is at your disposal?
IF I had the parts and only needed to off set bring the crank, what would be the issue you so love to LOL about all the time?

What if I or someone else felt like "wasting the money ?"
The question s stands and your not helping. Or is it that you can't help? Have you done this? Do you know what the cranks limits are? Or is it you have no idea?
I sure don't. You helping or just poking and trolling?
 
hey,..it is your post....go for it....and its your money...LOL...LOL...LOL...
 
You are all forgetting the most important thing. Re-harden the journals. It will cost you more to grind the crank and re-harden it then it would to just get a crank from Ohio crankshaft. Did you ever see a crank after you go through the hardening. A crank should look Chrome when polished you won't get that out of a unhardened shaft and it will hammer out and egg very fast with some serious boost or compression. A good heat treated bearing would be harder then the crank.

The most important thing on making serious HP is that it has to live. Or what good is it? Big muscles are useless if the heart can't take the extra load. Just a thought.

Also the only time you would want a GM sized rod is when you need a small pin because the block is decked to far for your stroke. It keep the pin under the compression rings. I tried it. Don't do it they are grenades with the pin pulled.
 
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